Diluting fuel-in-oil separating apparatus of internal combustion engine

ABSTRACT

The diluting fuel-in-oil separating apparatus includes an oil container (an oil pan) and a fuel eliminator (a heater, a bubble generator). The oil container contains lubricating oil of the internal combustion engine, and has a first compartment and a second compartment divided from the first compartment, such that the lubricating oil is introduced from the first compartment into the second compartment. The fuel eliminator eliminates fuel from the lubricating oil in the first compartment. The second compartment is provided with an oil passage having an oil pump supplying the lubricating oil from the second compartment to lubricated parts of the internal combustion engine.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of Japanese Patent Application Nos. 2008-124031 and 2008-124030, filed on May 9, 2008, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to diluting fuel-in-oil separating apparatuses of internal combustion engines and, more particularly, the present invention relates to a diluting fuel-in-oil separating apparatus of an internal combustion engine that can efficiently separate the fuel from the lubricating oil of the internal combustion engine while suppressing degradation of the oil.

2. Description of Related Art

Known conventional diluting fuel-in-oil separating apparatuses of internal combustion engines heat lubricating oil and separate the fuel from the lubricating oil by vaporization in order to suppress dilution of the lubricating oil which is caused by the mixed-in fuel (e.g., Related Art 1). Related Art 1 discloses such technology in which an oil heater is provided on an oil circuit of the internal combustion engine for heating the lubricating oil flowing in the oil circuit in order to separate the fuel by vaporization. Related Art 2 also discloses such technology in which a heater is provided at a bottom portion of an oil pan for heating the lubricating oil in the oil pan in order to separate the fuel by vaporization.

[Related Art 1] Japanese Laid-open Patent Publication No. 2004-190513

[Related Art 2] Japanese Laid-open Patent Publication No. 2004-340056

However, heat energy losses are significant in the technology disclosed in Related Art 1, since the heater heats a relatively large amount of the lubricating oil flowing in an oil passage that connects the oil pan to lubricated parts of the engine or in a bypass passage provided in the oil passage. In addition, the above-described problem is extremely conspicuous in the technology disclosed in Related Art 2, since all the oil in the oil pan is heated.

SUMMARY OF THE INVENTION

The present invention is provided to resolve the above-described problem. An advantage of the present invention is to provide a diluting fuel-in-oil separating apparatus of an internal combustion engine that can efficiently separate the fuel from the lubricating oil of the internal combustion engine while suppressing degradation of the oil.

The present invention is described hereinafter.

1. A diluting fuel-in-oil separating apparatus of an internal combustion engine includes an oil container configured to contain lubricating oil of the internal combustion engine and have a first compartment and a second compartment divided from the first compartment, such that the lubricating oil is introduced from the first compartment into the second compartment; and a fuel eliminator configured to eliminate fuel from the lubricating oil in the first compartment. The second compartment is provided with an oil passage having an oil pump configured to supply the lubricating oil from the second compartment to lubricated parts of the internal combustion engine.

2. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in above 1, the fuel eliminator includes a heater configured to heat the lubricating oil of the internal combustion engine; the first compartment is configured to contain the lubricating oil heated by the heater; and the second compartment is divided from the first compartment, such that the lubricating oil heated by the heater is introduced from the first compartment into the second compartment. The diluting fuel-in-oil separating apparatus of the internal combustion further includes an oil guide provided in a main body of the internal combustion engine and configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston among the lubricated parts of the internal combustion engine.

3. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 2 above, a volume of the oil contained in the first compartment is smaller than that contained in the second compartment.

4. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 2 above, the heater heats the lubricating oil flowing from the first compartment into the second compartment.

5. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 3 above, the heater heats the lubricating oil flowing from the first compartment into the second compartment.

6. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 2 above, a heat source for the heater is exhaust of the internal combustion engine.

7. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 3 above, a heat source for the heater is exhaust of the internal combustion engine.

8. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 1 above, the fuel eliminator includes a bubble generator configured to generate bubbles in the lubricating oil in the first compartment.

9. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 8 above, a volume of the oil contained in the first compartment is smaller than that contained in the second compartment.

10. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 8 above, a main body of the internal combustion engine is provided with an oil guide configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston, which is the lubricated part.

11. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 9 above, a main body of the internal combustion engine is provided with an oil guide configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston, which is the lubricated part.

12. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 8 above, the first compartment is disposed right below a piston, which is the lubricated part.

13. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 9 above, the first compartment is disposed right below a piston, which is the lubricated part.

14. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 8 above, the second compartment is disposed right below a passage configured to return the lubricating oil into the oil container after the lubricating oil lubricates an area around a head, which is the lubricated part. 15. According to the diluting fuel-in-oil separating apparatus of the internal combustion engine described in 9 above, the second compartment is disposed right below a passage configured to return the lubricating oil into the oil container after the lubricating oil lubricates an area around a head, which is the lubricated part.

According to the diluting fuel-in-oil separating apparatus of the internal combustion engine of the present invention, the fuel eliminator eliminates the fuel from the lubricating oil in the first compartment of the oil container. After the fuel elimination in the first compartment, the lubricating oil is guided into the second compartment, from which the lubricating oil is supplied to the lubricated parts by the oil pump via the oil passage. Thereby, the fuel can be efficiently separated from the lubricating oil while suppressing degradation of the oil. In addition, the fuel eliminator is the heater configured to heat the lubricating oil of the internal combustion engine. The first compartment contains the lubricating oil heated by the heater, and the second compartment is divided from the first compartment, such that the lubricating oil heated by the heater is introduced from the first compartment into the second compartment. In case that the oil guide is further provided in the main body of the internal combustion engine, after lubricating the piston, which is the lubricated part of the internal combustion engine, the lubricating oil is guided by the oil guide into the first compartment of the oil container, in which the heater heats the lubricating oil to accelerate vaporization of the fuel. As described above, since the lubricating oil having a relatively large amount of the mixed-in fuel is introduced into the first compartment by the oil guide, so that the oil having a relatively large amount of the fuel is selectively heated, the fuel separation is efficient compared to the conventional fuel separation by vaporization in which the lubricating oil is unselectively heated regardless of the amount of the fuel in the lubricating oil. In addition, since the lubricating oil having a relatively large amount of the mixed-in fuel is selectively heated, needless degradation of the lubricating oil by heating can be prevented. Furthermore, since the lubricating oil used to lubricate the piston does not directly flow into the second compartment, viscosity reduction by fuel dilution is small in the lubricating oil that is supplied to the lubricated parts. Thereby, poor lubrication is prevented in the lubricated parts. In case that the volume of the oil contained in the first compartment is smaller than that contained in the second compartment, the amount of the lubricating oil contained in the first compartment, which is heated by the heater therein, is relatively small; and the amount of the lubricating oil contained in the second compartment, which can be supplied to the lubricated parts therefrom, is relatively large. As a result, the fuel can be efficiently separated, and the total amount of the contained lubricating oil does not have to be needlessly large. In addition, in case that the heater heats the lubricating oil flowing from the first compartment into the second compartment, the fuel can be more efficiently separated by targeting a small amount of the lubricating oil, and needless degradation of the lubricating oil by heating can be further prevented. Furthermore, in case that the heat source for the heater is the exhaust of the internal combustion engine, a new heat source is not necessary, and an existing heat source can be utilized to separate the fuel from the lubricating oil by vaporization. In case that the fuel eliminator is the bubble generator, the bubble generator generates bubbles in the lubricating oil in the first compartment to accelerate vaporization of the fuel in the lubricating oil by the bubbles. After the fuel separation by vaporization in the first compartment, the lubricating oil is guided into the second compartment, from which the lubricating oil is supplied to the lubricated parts by the oil pump via the oil passage. As described above, since the bubble generator is provided so that bubbles accelerate vaporization of the fuel in the lubricating oil in the first compartment of the oil container, the fuel is efficiently separated from the lubricating oil while suppressing degradation of the oil, compared to the conventional fuel separation by vaporization in which the lubricating oil is heated. In addition, since the oil container is provided with the first compartment and the second compartment that is divided from the first compartment, such that the lubricating oil is introduced from the first compartment into the second compartment, the fully deaerated lubricating oil can be guided from the first compartment into the second compartment. As a result, the lubricating oil including bubbles is rarely suctioned into the oil pump, thereby suppressing the decrease in discharge capacity of the oil pump. In case that the volume of the oil contained in the first compartment is smaller than that contained in the second compartment, the fuel is more efficiently separated by targeting a relatively small amount of the lubricating oil in the first compartment, and a relatively large amount of the lubricating oil can be reserved in the second compartment, from which the lubricating oil is supplied to the lubricated parts. In case that the main body of the internal combustion engine is provided with the oil guide configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates the piston, which is the lubricated part, the fuel can be more efficiently separated from the lubricating oil in the first compartment. This is because the lubricating oil having a relatively large amount of the fuel is guided into the first compartment by the oil guide. In case that the first compartment is disposed right below the piston, which is the lubricated part, the fuel can be more efficiently separated from the lubricating oil in the first compartment. This is because the lubricating oil having a relatively large amount of the fuel directly falls into the first compartment. In case that the second compartment is disposed right below the passage configured to return the lubricating oil into the oil container after the lubricating oil lubricates the area around the head, which is the lubricated part, the lubricating oil is easily reserved in the second compartment. This is because the lubricating oil used to lubricate the area around the head and having a relatively small amount of the mixed-in fuel directly returns to the second compartment.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

FIG. 1 is an illustrative view showing a diluting fuel-in-oil separating apparatus according to a first embodiment;

FIG. 2 is an illustrative view showing the diluting fuel-in-oil separating apparatus having an alternative configuration;

FIG. 3 is an illustrative view further showing the diluting fuel-in-oil separating apparatus having an alternative configuration;

FIG. 4 is a longitudinal sectional view of the diluting fuel-in-oil separating apparatus according to a second embodiment;

FIG. 5 is a longitudinal sectional view of essential parts of a diluting fuel-in-oil separating apparatus according to a third embodiment;

FIG. 6 is a longitudinal sectional view of a bubble generator having an alternative configuration;

FIG. 7 is a longitudinal sectional view of the diluting fuel-in-oil separating apparatus having an alternative configuration; and

FIG. 8 is a transverse sectional view of an oil pan having an alternative configuration.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description is taken with the drawings making apparent to those skilled in the art how the forms of the present invention may be embodied in practice.

1. Diluting Fuel-In-Oil Separating Apparatus of Internal Combustion Engine

A diluting fuel-in-oil separating apparatus of an internal combustion engine according to a present embodiment 1 includes a heater (described as an example of a “fuel eliminator” according to the present invention), an oil container, and an oil guide, which are to be described below.

As long as the “heater” heats lubricating oil in the internal combustion engine, the structure, the heating method, the heat source, and the like thereof are not particularly specified. Examples of the heater include an exhaust pipe exhausting exhaust gas from the internal combustion engine, an electric heater, and the like. In terms of use of an existing heat source, the exhaust pipe of the internal combustion engine is preferable.

As long as the “oil container” is provided with a first compartment containing the lubricating oil heated by the heater and a second compartment divided from the first compartment, such that the lubricating oil heated by the heater is introduced from the first compartment into the second compartment, the structure, the shape, the material, the compartment configuration, and the like thereof are not particularly specified. Examples of the oil container include an oil pan provided in a lower portion of a main body of the internal combustion engine, an oil tank provided separately from the main body of the internal combustion engine, and the like.

Exemplary compartment configurations of the first and second compartments include: (1) a configuration in which a bottom wall of the oil container is raised upward in parallel with an axial direction of a crankshaft (refer to FIGS. 1, 3, and the like); and (2) a configuration in which the bottom wall of the oil container is raised upward orthogonally to the axial direction of the crankshaft (refer to FIG. 2 and the like). In the configurations (1) and (2), for example, the lubricating oil, flows from the first compartment, crosses over an upper end of the raised bottom wall, and is introduced into the second compartment.

Exemplary methods of heating the lubricating oil by the heater include: (1) a method in which all the lubricating oil contained in the first compartment is heated; and (2) a method in which the lubricating oil is heated while flowing from the first compartment into the second compartment. In terms of efficient fuel separation by targeting a small amount of the lubricating oil, the heating method (2) is preferable.

The second compartment is provided with an oil passage having an oil pump that supplies the lubricating oil from the second compartment to the lubricated parts of the internal combustion engine. In case that the oil container is the oil pan, the oil passage is provided with an oil strainer at one end, and the oil strainer is disposed in the oil pan.

Examples of the oil passage include any combination of one or more of the following: a pipe, a passage provided in the main body or a mechanism unit of the internal combustion engine, space, and the like. Examples of the oil pump include a trochoid pump, an internal gear pump, an external gear pump, an inner gear pump, and the like. The oil pump may be operated, for example, by a driving force of the internal combustion engine or by a drive source other than the internal combustion engine.

Herein, for example, a volume of the oil contained in the first compartment may be smaller than that contained in the second compartment. It is preferable that a ratio (C1/C2) between the volume of the oil containing in the first compartment (C1) and the volume of the oil contained in the second compartment (C2) be 0.2-0.5 (specifically, 0.25-0.3). The reason for this is that the fuel is more efficiently separated by targeting a relatively small amount of the lubricating oil in the first compartment, and a larger amount of the lubricating oil can be reserved in the second compartment. For example, the oil container may be provided with a stepped bottom, such that the bottom wall of the first compartment is on an upper level, and that the bottom wall of the second compartment is on a lower level. Thereby, the volume of the oil contained in the first compartment is smaller than that contained in the second compartment.

As long as the “oil guide” guides the lubricating oil into the first compartment after the lubricating oil lubricates a piston, which is the lubricated part of the internal combustion engine, the structure, the shape, the material, and the like thereof are not particularly specified. In addition to the oil guide, the internal combustion engine may be provided, in the main body, with: (a) an alternative oil guide guiding the lubricating oil returning to the oil container via a connecting path into the second compartment, the connecting path being formed in a cylinder block of the engine and connecting a crankchamber into a head cover; or (b) an alternative oil guide guiding the lubricating oil returning to the oil container via a chain case or belt case of the engine into the second compartment. Thereby, the lubricating oil having little mixed-in fuel can be guided and introduced into the second compartment by the alternative oil guide, further improving efficiency of fuel separation from the lubricating oil in the first compartment. In terms of further improvement of the separation efficiency, a combination of the configurations (a) and (b) is preferable.

In the configurations (1) and (2), (a) the second compartment may be disposed right below the connecting path formed in the cylinder block of the engine and connecting the crankchamber into the head cover; or (b) the second compartment may be disposed right below the chain case or belt case of the engine. Thereby, the lubricating oil having little mixed-in fuel can fall into the second compartment, further improving efficiency of fuel separation from the lubricating oil in the first compartment. In terms of further improvement of the separation efficiency, a combination of the configurations (a) and (b) is preferable.

Examples of the “lubricated parts of the internal combustion engine” besides the piston include a crankshaft, a connecting rod, a camshaft, a driving mechanism, and the like. The lubricating oil returning to the oil container after lubricating an area around the piston includes a relatively large amount of the mixed-in fuel that has leaked out of gaps in inner walls of cylinders, the lubricated area including the crankshaft, the connecting rod, the piston, and the like among the above-mentioned lubricated parts. Meanwhile, the lubricating oil returning to the oil container after lubricating an area around a head includes little mixed-in fuel, the lubricated area including the camshaft, the driving mechanism, and the like. In addition, the lubricating oil normally returns to the oil container via a gap between the piston and the cylinder after lubricating the area around the piston. Meanwhile, after lubricating the area around the head, the lubricating oil normally returns to the oil container via the connecting path formed in the cylinder block and cylinder head of the engine and connecting the crankchamber to the space inside the head cover, or via the chain case or belt case of the engine. The same applies to the diluting fuel-in-oil separating apparatus of the internal combustion engine of an embodiment 2 that is to be described below.

In case that, in addition to a primary fuel injection into the cylinder in the vicinity of a compression top dead center, a secondary fuel injection into the cylinder before and after the primary fuel injection (e.g., a pilot injection, a post injection, and the like) is performed in a cylinder injection type internal combustion engine, the injected fuel easily attaches to a surface of the inner wall of the cylinder, and the attached fuel easily enters in the lubricating oil. Therefore, the diluting fuel-in-oil separating apparatus of the internal combustion engine according to the present embodiment is suitably used as a diluting fuel-in-oil separating apparatus of a cylinder injection type internal combustion engine that performs a secondary fuel injection before and after a primary fuel injection. The same applies to the diluting fuel-in-oil separating apparatus of the internal combustion engine of the embodiment 2 that is to be described below.

The diluting fuel-in-oil separating apparatus of the internal combustion engine according to the present embodiment 2 includes the oil container and a bubble generator (described as an example of a “fuel eliminator” according to the present invention) that are to be described below.

As long as the “oil container” contains the lubricating oil of the internal combustion engine, and is provided with the first compartment and the second compartment divided from the first compartment, such that the lubricating oil is introduced from the first compartment into the second compartment, the structure, the shape, the material, and the like thereof are not particularly specified. Examples of the oil container include the oil pan provided in a lower portion of the main body of the internal combustion engine, the oil tank provided separately from the main body of the internal combustion engine, and the like.

Exemplary compartment configurations of the first and second compartments include: (1) a configuration in which the first and second compartments are divided by a partition wall leading upward from the bottom wall of the oil container to be horizontally disposed (refer to FIG. 4); and (2) a configuration in which the oil container is provided with an oil vessel in an upper portion, such that an inner region of the oil vessel is the first compartment and that an inner region of a lower portion of the oil container is the second compartment, and the first and second compartments are vertically disposed (refer to FIG. 5). According to the configuration (1), the height of the oil container can be reduced, and the lubricating oil can be smoothly introduced from the first compartment into the second compartment. According to the configuration (2), the width of the oil container can be reduced, and the fully deaerated lubricating oil can be introduced from the first compartment into the second compartment.

In the configuration (1), for example, the lubricating oil in the first compartment can be introduced into the second compartment via the connecting path formed on an upper end of the partition wall. Thereby, the fully deaerated lubricating oil can be smoothly introduced into the second compartment. Examples of the connecting path include the upper end of the partition wall, a connecting hole, and the like.

For example, substantially all the lubricating oil returning to the oil container after lubricating the lubricated parts of the internal combustion engine can be introduced into the first compartment. However, it is preferable that a portion of the lubricating oil returning to the oil container after lubricating a predetermined area of the lubricated parts of the internal combustion engine (e.g., an area around the piston and the like) be introduced into the first compartment. The reason for this is to improve efficiency of fuel separation from the lubricating oil.

The second compartment is provided with the oil passage having the oil pump that supplies the lubricating oil from the second compartment to the lubricated parts of the internal combustion engine. In case that the oil container is the oil pan, the oil passage is provided with the oil strainer at one end, and the oil strainer is disposed in (connected to) the oil pan. Examples of the oil passage include any combination of one or more of the following: a pipe, a passage provided in the main body or the mechanism unit of the internal combustion engine, space, and the like. Examples of the oil pump include a trochoid pump, an internal gear pump, an external gear pump, an inner gear pump, and the like. The oil pump may be operated, for example, by a driving force of the internal combustion engine or by a drive source other than the internal combustion engine.

Herein, for example, the volume of the oil contained in the first compartment may be smaller than that contained in the second compartment. It is preferable that the ratio (C1/C2) between the volume of the oil contained in the first compartment (C1) and the volume of the oil contained in the second compartment (C2) be 0.2-0.5 (specifically, 0.25-0.3). The reason for this is that the fuel is more efficiently separated in the first compartment, and a larger amount of the lubricating oil can be reserved in the second compartment. In the configuration (1), for example, the oil container may be provided with a stepped bottom, such that the bottom wall of the first compartment is on an upper level, and that the bottom wall of the second compartment is on a lower level. Thereby, the volume of the oil contained in the first compartment is smaller than that contained in the second compartment, further reducing the height of the oil container.

As long as the “bubble generator” generates bubbles in the lubricating oil in the first compartment, the structure, the bubble generating configuration, timing, and the like thereof are not particularly specified. Herein, vaporization of the fuel in the lubricating oil could be hindered by viscosity resistance of the lubricating oil. However, vaporization of the fuel in the lubricating oil is accelerated by the bubbles in the lubricating oil generated by the bubble generator, since the fuel is enveloped or lifted by the bubbles.

Exemplary configurations of the bubble generator include: (1) a configuration in which the bottom wall and/or sidewalls configuring the first compartment of the oil container is provided with a plurality of bubble pores, to which one end of an air passage is connected, while the other end of the air passage is connected to an air source such as a compressor and the like (refer to FIGS. 4 and 5); and (2) a configuration in which the first compartment of the oil container is provided with a bubble tube, to which the one end of the air passage is connected while the other end of the air passage is connected to an air source such as compressor and the like, the bubble tube being provided with a plurality of bubble nozzles (refer to FIG. 6).

In the configurations (1) and (2), a control valve may be provided in the air passage to open and close the air passage, and the control valve may be controlled to open and close by a controller based on engine speed, oil pressure, oil temperature, and the like of the internal combustion engine. As a result, the fuel can be separated by targeting when the degree of fuel dilution in the lubricating oil of the internal combustion engine is relatively high.

The bubbles generated by the bubble generator may have a diameter of, for example, 0.1-5 mm (preferably, 1-2 mm). Thereby, the fuel can be more efficiently separated from the lubricating oil.

Exemplary configurations of the diluting fuel-in-oil separating apparatus of an internal combustion engine according to the present embodiment 2 include: (1) a configuration in which an oil guide guiding the lubricating oil into the first compartment after the lubricating oil lubricates the piston, which is the lubricated part, is provided in the main body of the internal combustion engine (refer to FIGS. 4 and 7); (2) a configuration in which the first compartment is disposed right below the piston, which is the lubricated part (refer to FIG. 5); and (3) a configuration in which the second compartment is disposed right below a passage returning the lubricating oil into the oil container after the lubricating oil lubricates the area around the head (refer to FIGS. 4 and 7). Among the above, combinations of the configurations (1) and (3) and the configurations (2) and (3) are preferable. The reason for this is that the fuel separation efficiency is further improved in the first compartment, and the lubricating oil is easily reserved in the second compartment. In the configuration (1), examples of the main body of the internal combustion engine include the oil container, a crankcase, and the like.

In the configurations (1) and (2), for example, the internal combustion engine is provided, in the main body, with: (a) the alternative oil guide guiding the lubricating oil returning to the oil container via the connecting path into the second compartment, the connecting path being formed in the cylinder block or cylinder head of the engine and connecting the crankchamber to the space inside the head cover; or (b) the alternative oil guide guiding the lubricating oil returning to the oil container via the chain case or belt case of the engine into the second compartment. Thereby, the lubricating oil having little mixed-in fuel can be guided and introduced into the second compartment by the alternative oil guide, further improving efficiency of fuel separation from the lubricating oil in the first compartment. In terms of further improvement of the separation efficiency, a combination of the configurations (a) and (b) is preferable.

Examples of the configuration (3) include: (a) a configuration in which the second compartment is disposed right below the connecting path formed in the cylinder block and cylinder head of the engine and connecting the crankchamber to the space inside the head cover (refer to FIG. 4); and (b) a configuration in which the second compartment is disposed right below the chain case or belt case of the engine (refer to FIG. 7). In terms of easier reservation of the lubricating oil, a combination of the configurations (a) and (b) is preferable.

EMBODIMENT

Hereinafter, first to third embodiments of the present invention will be described in detail with reference to the drawings. In the first to third embodiment, a cylinder injection type internal combustion engine is described as an example of an “internal combustion engine”according to the present invention, the cylinder injection type internal combustion engine performing a secondary injection before and after a primary injection.

(1) Configuration of Engine

As shown in FIG. 1, an engine 1 according to the first embodiment includes a cylinder block 1 a provided with a cylinder 2 and a cylinder head 1 b fixed to an upper portion of the cylinder block 1 a. A piston 3 is reciprocably supported inside the cylinder 2 of the cylinder block 1 a. A crankcase 1 c rotatably supporting a crankshaft 4 is fixed to a lower portion of the cylinder block 1 a. The crankshaft 4 is connected to the piston 3 via a connecting rod 5. A combustion chamber 6 is provided above the piston 3, the combustion chamber 6 being enclosed by a top surface of the piston 3, wall surfaces of the cylinder head 1 b, and wall surfaces of the cylinder 2.

The cylinder head 1 b is provided with an intake port 8 a and exhaust port 8 b. One end of the intake port 8 a is connected to an intake pipe 7 a while the other thereof is connected to the combustion chamber 6. One end of the exhaust port 8 b is connected to an exhaust pipe 7 b while the other end thereof is connected to the combustion chamber 6. The cylinder head 1 b is also provided with an intake valve 9 a opening and closing the intake port 8 a and an exhaust valve 9 b opening and closing the exhaust port 8 b. In addition, the cylinder head 1 b rotatably supports camshafts 10 a and 10 b, the camshafts 10 a and 10 b driving the intake valve 9 a and exhaust valve 9 b, respectively. A cylinder head cover id covering the above-described valve gear is installed on an upper portion of the cylinder head 1 b. One end of the intake pipe 7 a is connected to an air cleaner box 11. A throttle valve 12 is provided in the intake pipe of 7 a, the throttle valve 12 adjusting a volume of intake air flowing in the intake pipe 7 a.

One end of a first reflux path 15 is connected to a downstream side of the throttle valve 12 of the intake pipe 7 a while the other end thereof is connected to a space 13 inside the cylinder head cover ld via a PCV valve 15 a. In addition, one end of a second reflux path 16 is connected to an upstream side of the throttle valve 12 of the intake pipe 7 a while the other end thereof is connected to the space 13 inside the cylinder head cover 1 d.

An oil pan 17 containing lubricating oil (described as an example of an “oil container” according to the present invention) is provided at a lower portion of the crankcase 1 c. The oil pan 17 is connected to lubricated parts of the engine 1 via a circulation path (not shown) including an oil passage 18.

(2) Configuration of Diluting Fuel-In-Oil Separating Apparatus

As shown in FIG. 1, a diluting fuel-in-oil separating apparatus 20 according to the first embodiment is provided with the oil pan 17 containing the lubricating oil. A raised portion 17 a having a circular arc cross-section is formed on a bottom wall of the oil pan 17, along a liner direction in parallel with an axial direction of the crankshaft 4. An interior of the oil pan 17 is divided by the raised portion 17 a into a first compartment 21 and second compartment 22. In the oil pan 17, the level of the bottom wall of the first compartment 21 is higher than that of the bottom wall of the second compartment 22. A volume of the oil contained in the first compartment 21 (C1) is set to approximately 1.2 liter. A volume of the oil contained in the second compartment 22 (C2) is set to approximately 4 liter. Accordingly, a ratio (C1/C2) between the volume of the oil contained in the first compartment 21 (C1) and the volume of the oil contained in the second compartment 22 (C2) is 0.3. A lower exhaust pipe 23 (described as an example of a “fuel eliminator” and a “heater” according to the present invention) exhausting exhaust gas of the engine 1 is latently provided outside a main body of the engine 1, below the raised portion 17 a.

An oil strainer 18 a provided at one end of the oil passage 18 is disposed in the second compartment 22. An oil pump 18 b is provided in the oil passage 18, the oil pump 18 b supplying the lubricating oil from the second compartment 22 to the lubricated parts of the engine 1. The second compartment 22 is disposed right below a connecting path 24 formed in the cylinder block 1 a and cylinder head 1 b of the engine 1 and connecting a crankchamber 14 to the space 13 inside the cylinder head cover 1 d.

A plate-shaped baffle plate 25 is provided at on an upper portion of the oil pan 17, which is a lower portion of the crankcase 1 c, the baffle plate 25 guiding the lubricating oil, which is returning to the oil pan 17 via a gap between the piston 3 and cylinder 2, into the first compartment 21.

(3) Function of Diluting Fuel-In-Oil Separating Apparatus

Hereinafter, the function of the diluting fuel-in-oil separating apparatus 20 having the above-described configuration will be described. In the first embodiment, since the cylinder injection type internal combustion engine 1 performing a secondary injection before and after a primary injection is employed, a ratio of dilution by fuel that is attached to an inner peripheral surface of the cylinder and enters in the lubricating oil increases in the lubricating oil returning to the oil pan 17 via the gap between the piston 3 and cylinder 2.

During engine operation, the lubricating oil circulating in an area around the piston 1 flows through the gap between the piston 3 and cylinder 2, and is guided by the baffle plate 25, so that the lubricating oil returns to the first compartment 21 of the oil pan 17. The area around the piston includes the crankshaft 4, connecting rod 5, piston 3, and the like, which are the lubricated parts of the engine 1. Meanwhile, the lubricating oil circulating in an area around a head returns to the second compartment 22 of the oil pan 17 via the connecting path 24 or via a chain case or belt case of the engine 1 (not shown). The area around the head includes camshafts 10 a and 10 b, a driving mechanism, and the like, which are the lubricated parts of the engine 1. The lubricating oil guided into the first compartment 21 by the baffle plate 25, contained therein, and flowing therefrom crosses over an upper end of the raised portion 17 a of the bottom wall of the oil pan 17, so that the lubricating oil is introduced into the second compartment 22. At that time, the lubricating oil flowing along a wall surface of the raised portion 17 a is heated by radiant heat of the exhaust gas passing through the lower exhaust pipe 23 running below the raised portion 17 a so that the mixed-in fuel in the lubricating oil is vaporized.

Meanwhile, the lubricating oil that does not fall onto the baffle plate 25 after lubricating the lubricated parts (i.e., the lubricating oil and the like flowing back from the inside of the cylinder head cover 1 d into the oil pan 17 via the connecting path 24 after lubricating the lubricated parts, such as camshafts 10 a and 10 b, and the like at an upper portion of the engine 1) is directly introduced into the second compartment 22 without flowing through the first compartment 21. The lubricating oil having reached the second compartment 22 is suctioned into the oil strainer 18 a, and is forcibly pressure-fed by the oil pump 18 b again into each of the lubricated parts of the engine 1 through the oil passage 18.

The vaporized fuel is mixed with blow-by gas, and is sent from the crankchamber 14 to the space 13 inside the cylinder head cover 1 d via the connecting path 24. The blow-by gas flows back to the intake pipe 7 a via the first reflux path 15 under a low load diving condition of the engine 1 (a driving condition when the throttle valve opening is small). The blow-by gas flows back to the intake pipe 7 a via the second reflux path 16 in addition to the first reflux path 15 under a high load driving condition of the engine 1 (a driving condition when the throttle valve opening is large). Under the low load driving condition of the engine 1, fresh air flowing upstream of the throttle valve 12 of the intake pipe 7 a via the second reflux path 16 is suctioned into the space 13 inside the cylinder head cover 1 d, and the blow-by gas in the space 13 is ventilated.

(4) Effect of The Embodiment

In the first embodiment, after lubricating the piston 3, which is the lubricated part of the engine 1, the lubricating oil is guided by the baffle plate 25 into the first compartment 21 of the oil pan 17 and contained therein. The lubricating oil contained in the first compartment 21 crosses over the upper end of the raised portion 17 a of the bottom wall of the oil pan 17, so that the lubricating oil is introduced into the second compartment 22. At that time, the lubricating oil is heated by the lower exhaust pipe 23, so that vaporization of the fuel accelerated. As described above, since the lubricating oil having a relatively large amount of the mixed-in fuel is introduced into the first compartment 21 by the baffle plate 25, so that the lubricating oil having a relatively large amount of the mixed-in fuel is selectively heated, the fuel separation is efficient compared to the conventional fuel separation by vaporization, in which the lubricating oil is unselectively heated regardless of the amount of the fuel in the lubricating oil. In addition, needless degradation of the lubricating oil by heating is prevented.

In addition, in the first embodiment, since the lubricating oil used to lubricate the piston 3 (i.e., the lubricating oil having a relatively large amount of the fuel) does not directly flow into the second compartment 22, viscosity reduction by fuel dilution is small in the lubricating oil that is supplied to the lubricated parts. Thereby, poor lubrication is prevented in each of the lubricated parts.

Further, in the first embodiment, the second compartment 22 is disposed right below the connecting path 24 formed in the cylinder block 1 a and cylinder head 1 b of the engine 1 and connecting the crankchamber 14 to the space 13 inside the cylinder head cover id. Thereby, the lubricating oil having little mixed-in fuel can be dropped and introduced into the second compartment 22 by the connecting path 24, further improving efficiency of fuel separation from the lubricating oil in the first compartment 21. In addition, since the viscosity reduction by the fuel dilution is small in the lubricating oil that is supplied to the lubricated parts, poor lubrication is prevented in each of the lubricated parts.

Furthermore, in the first embodiment, since the volume of the oil contained in the first compartment 21 is smaller than that contained in the second compartment 22, an amount of the lubricating oil contained in the first compartment 21 (i.e., the lubricating oil contained therein to be heated) is relatively small. Meanwhile, an amount of the lubricating oil contained in the second compartment 22, which is usable to lubricate the lubricated parts, is relatively large. As a result, the fuel can be efficiently separated, and the total amount of the contained lubricating oil does not have to be needlessly large.

Moreover, in the first embodiment, since the lubricating oil flowing from the first compartment 21 into the second compartment 22 is heated by the lower exhaust pipe 23, the fuel is more efficiently separated by targeting a smaller amount of the lubricating oil. In addition, needless degradation of the lubricating oil by heating is further prevented. In the present embodiment, since the lower exhaust pipe 23 exhausting the exhaust gas from the engine 1 is used as a heater, a new heat source is not necessary for the fuel separation, and an existing heat source can be utilized to separate the fuel from the lubricating oil by vaporization.

The present invention is not limited to the first embodiment, and various modifications may be made depending on the purpose and use without departing from the scope of the invention. In short, although the first compartment 21 and second compartment 22 may be divided in a liner direction in parallel with the axial direction of the crankshaft 4 of the engine 1 in the first embodiment, the compartment configuration is not limited to the same. For example, as shown in FIG. 2, the first compartment 21 and second compartment 22 may be divided in a liner direction that is orthogonal to the axial direction of the crankshaft 4. In the above-described case, when the engine 1 has a chain 26 at a shaft end of the crankshaft 4 and a chain case 27 through which the lubricating oil and the like flow back into the oil pan 17 after lubricating the chain 26, the second compartment 22 may be provided at the chain case 27 side, the chain 26 transmitting power to the camshafts 10 a and 10 b. Thereby, the lubricating oil having little fuel flowing back to the oil pan 17 via the chain case 27 is directly introduced into the second compartment 22.

Although the lubricating oil flowing from the first compartment 21 into the second compartment 22 is heated in the first embodiment, the present invention is not limited to the same. For example, all the lubricating oil contained in the first compartment 21 may be heated.

Although the lower exhaust pipe 23 is described as an example of the heater in the first embodiment, the present invention is not limited to the same. For example, an electric heater 23′ having an electric heating wire 23′a therein may be employed. In this case, the lubricating oil flowing from the first compartment 21 into the second compartment 22 may be heated. Alternatively, as shown in FIG. 3, all the lubricating oil contained in the first compartment 21 may be heated.

(Second Embodiment)

(1) Configuration of Engine

As shown in FIG. 4, the engine 1 according to the second embodiment includes the cylinder block la provided with the cylinder 2 and the cylinder head 1 b fixed to the upper portion of the cylinder block 1 a. The piston 3 is reciprocably supported inside the cylinder 2 of the cylinder block 1 a. The crankcase 1 c rotatably supporting the crankshaft 4 is also fixed to the lower portion of the cylinder block 1 a. The crankshaft 4 is connected to the piston 3 via the connecting rod 5. The combustion chamber 6 is provided above the piston 3, the combustion chamber 6 being enclosed by the top surface of the piston 3, the wall surfaces of the cylinder head 1 b, and the wall surfaces of the cylinder 2.

The cylinder head 1 b is provided with the intake port 8 a and exhaust port 8 b. One end of the intake port 8 b is connected to the intake pipe 7 a while the other end thereof is connected to the combustion chamber 6. One end of the exhaust port 8 b is connected to the exhaust pipe 7 b while the other end is connected to the combustion chamber 6. The cylinder head 1 b is also provided with the intake valve 9 a opening and closing the intake port 8 a and the exhaust valve 9 b opening and closing the exhaust port 8 b. In addition, the cylinder head 1 b rotatably supports the camshafts 10 a and 10 b, the camshafts 10 a and 10 b driving the intake valve 9 a and exhaust valve 9 b, respectively. The cylinder head cover ld covering the above-described valve gear is installed on the upper portion of the cylinder head 1 b. One end of the intake pipe 7 a is connected to the air cleaner box 11. The throttle valve 12 is provided in the intake pipe of 7 a, the throttle valve 12 adjusting the volume of intake air flowing in the intake pipe 7 a.

One end of the first reflux path 15 is connected to the downstream side of the throttle valve 12 of the intake pipe 7 a while the other end thereof is connected to the space 13 within the cylinder head cover 1 d via the PCV valve 15 a. In addition, one end of the second reflux path 16 is connected to the upstream side of the throttle valve 12 of the intake pipe 7 a while the other end thereof is connected to the space 13 within the cylinder head cover 1 d.

An oil pan 18 containing the lubricating oil (described as an example of an “oil container” according to the present invention) is provided at the lower portion of the crankcase 1 c. The oil pan 18 is connected to lubricated parts of the engine 1 via the circulation path (not shown) including an oil passage 19.

(2) Configuration of Diluting Fuel-In-Oil Separating Apparatus

As shown in FIG. 4, the diluting fuel-in-oil separating apparatus 20 according to the second embodiment is provided with the oil pan 18 having the first compartment 21 and second compartment 22. A partition wall 24 leading upward from the bottom wall 23 of the oil pan 18 divides the oil pan 18 into the first compartment 21 and second compartment 22, which are contiguous in a horizontal direction. In addition, the bottom wall 23 is stepped, such that the level of the bottom wall 23 a of the first compartment 21 is higher than that of the bottom wall 23 b of the second compartment 22. A volume of the oil contained in the first compartment 21 (C1) is set to approximately 1.2 liter. A volume of the oil contained in the second compartment 22 (C2) is set to approximately 4 liter. Accordingly, a ratio (C1/C2) between the volume of the oil contained in the first compartment 21 (C1) and the volume of the oil contained in the second compartment 22 (C2) is 0.3.

A bubble generator 26 generating bubbles in the lubricating oil in the first compartment 21 (described as an example of a “fuel eliminator” according to the present invention) is connected to the first compartment 21. The bubble generator 26 includes a plurality of bubble pores 27 formed through the bottom wall 23 a of the first compartment 21. The plurality of bubble pores 27 have a diameter of approximately 1 mm, and are formed at an equal pitch over an entire surface area of the bottom wall 23 a. A lower wall 29. forming an air space 28 is provided below the bottom wall 23 a of the oil pan 18, the air space 28 continuing into each of the bubble pores 27. One end of an air piping 31 is connected to a compressor 30 while the other end thereof is connected to the air space 28. A controller 32 and a solenoid valve 33 are provided in the air piping 31. The controller 32 is configured with a CPU, a RAM, a ROM, and the like. The solenoid valve 33 is electrically connected to the controller 32. The controller 32 opens the air piping 31 by opening the solenoid valve 33 when the engine starts. Meanwhile, the controller 32 closes the air piping 31 by closing the solenoid valve 33 when the engine stops.

An oil strainer 35 provided at one end of the oil passage 19 is disposed in the second compartment 22. An oil pump 36 is provided in the oil passage 19, the oil pump 36 supplying the lubricating oil from the second compartment 22 to the lubricated parts of the engine 1. The second compartment 22 is disposed right below a connecting path 37 formed in the cylinder block 1 a and cylinder head 1 b of the engine 1, and connecting the crankchamber 14 to the space 13 inside the cylinder head cover 1 d.

A plate-shaped oil guide 38 is provided at a lower portion of the crankcase 1 c and an upper portion of the oil pan 18. The oil guide 38 guides the lubricating oil into the first compartment 21 when the lubricating oil returns to the oil pan 18 via the gap between the piston 3 and cylinder 2.

(3) Function of Diluting Fuel-In-Oil Separating Apparatus

Hereinafter, the function of the diluting fuel-in-oil separating apparatus 20 having the above-described configuration will be described. In the second embodiment, since the cylinder injection type internal combustion engine 1 performing a secondary injection before and after a primary injection is employed. Therefore, a ratio of dilution by fuel the fuel that is attached to the inner peripheral surface of the cylinder and enters in the lubricating oil increases in the lubricating oil returning to the oil pan 18 via the gap between the piston 3 and cylinder 2.

During engine operation, the lubricating oil circulating in the area around the piston flows through the gap between the piston 3 and cylinder 2, and is guided by the oil guide 38, so that the lubricating oil returns to the first compartment 21 of the oil pan 18. The area around the piston includes the crankshaft 4, connecting rod 5, piston 3, and the like, which are the lubricated parts of the engine 1. Meanwhile, the lubricating oil circulating in an area around the head returns to the second compartment 22 of the oil pan 18 via the connecting path 37 or via the chain case or belt case of the engine 1 (not shown). The area around the head includes the camshafts 10 a and 10 b, the driving mechanism, and the like, which are the lubricated parts of the engine 1.

During engine operation, the compressor 30 sends compressed air to the air piping 31 in an open state and then to the bubble pores 27 via the air space 28 so as to generate a large number of bubbles in the lubricating oil in the first compartment 21. The fuel in the lubricating oil in the first compartment 21 is enveloped or lifted by the generated bubbles, so that vaporization of the fuel is accelerated against viscosity resistance of the lubricating oil. The vaporized fuel is mixed with the air naturally deaerated from the lubricating oil and the blow-by gas, and is sent from the crankchamber 14 to the space 13 inside the cylinder head cover 1 d via the connecting path 37. The blow-by gas flows back to the intake pipe 7 a via the first reflux path 15 under a low load diving condition of the engine 1 (a driving condition when the throttle valve opening is small). The blow-by gas flows back to the intake pipe 7 a via the second reflux path 16 in addition to the first reflux path 15 under a high load driving condition of the engine 1 (a driving condition when the throttle valve opening is large). Under the low load driving condition of the engine 1, fresh air flowing upstream of the throttle valve 12 of the intake pipe 7 a via the second reflux path 16 is suctioned into the space 13 inside the cylinder head cover id, and the blow-by gas in the space 13 is ventilated.

After the fuel separation in the first compartment 21, the lubricating oil in the first compartment 21 crosses over an upper end of the partition wall 24, so that the lubricating oil is introduced into the second compartment 22. The lubricating oil in the second compartment 22 is forcibly pressure-fed by an oil pump 36 into the lubricated parts of the engine 1 through the oil passage 19 via the oil strainer 35.

(4) Effect of The Embodiment

As described above, in the second embodiment, the oil pan 18 is provided with the bubble generator 26 so as to accelerate vaporization of the fuel in the lubricating oil by bubbles in the first compartment 21 of the oil pan 18. Therefore, compared to the conventional fuel separation by vaporization in which the lubricating oil is heated, the fuel can be efficiently separated from the lubricating oil while degradation of the lubricating oil is prevented. In addition, the oil pan 18 is provided with the first compartment 21 and the second compartment 22 that is divided from the first compartment 21, such that the lubricating oil is introduced from the first compartment 21 into the second compartment 22, the fully deaerated lubricating oil can be guided from the first compartment 21 into the second compartment 22. As a result, the lubricating oil including bubbles is rarely suctioned into the oil pump 36, and thereby malfunctions such as heat generation and the like due to the breaking of the bubbles by oil pressure pulsation or oil pressure are prevented. In addition, the decrease in discharge capacity of the oil pump 36 is prevented. The fuel separated from the lubricating oil by vaporization is mixed with the air naturally deaerated from the lubricating oil and the blow-by gas, and is sent from the crankchamber 14 to the space 13 inside the cylinder head cover id via the connecting path 37. Thereby, ventilation of the blow-by gas is accelerated in the space 13 regardless of the driving condition of the engine 1 (i.e., a degree of the opening of the throttle valve 12).

Also, in the second embodiment, since the volume of the oil contained in the first compartment 21 (C1) is smaller than that contained in the second compartment 22 (C2), the fuel is more efficiently separated by targeting a relatively small amount of the lubricating oil in the first compartment 21. In addition, a relatively large amount of the lubricating oil is reserved in the second compartment 22, from which the lubricating oil is supplied to the lubricated parts. Particularly, the bottom wall 23 of the oil pan 18 is stepped, such that the level of the bottom wall 23 a of the first compartment 21 is higher than that of the bottom wall 23 b of the second compartment 22, so as to make the volume of the oil contained in the first compartment 21 (C1) smaller than that contained in the second compartment 22 (C2). Thereby, the height of the oil pan 18 can be reduced.

The oil guide 38 is provided in the oil pan 18 and the crankcase 1 c, the oil guide 38 guiding the lubricating oil into the first compartment 21 when the lubricating oil returns to the oil pan 18 via the gap between the piston 3 and cylinder 2, which are the lubricated parts. Thereby, the lubricating oil having a relatively large amount of the mixed-in fuel after lubricating the area around the piston is guided into the first compartment 21 by the oil guide 38, further improving efficiency of fuel separation from the lubricating oil in the first compartment 21.

Further, in the second embodiment, the second compartment 22 is disposed right below the connecting path 37 formed in the cylinder block 1 a and cylinder head 1 b of the engine 1 and connecting the crankchamber 14 to the space 13 inside the cylinder head cover 1 d. Thereby, the lubricating oil having little mixed-in fuel directly falls into the second compartment 22, further improving efficiency of fuel separation from the lubricating oil in the first compartment 21.

Furthermore, in the second embodiment, since the partition wall 24 leading upward from the bottom wall 23 of the oil pan 18 divides the oil pan 18 into the first compartment 21 and second compartment 22 in a horizontal direction, the height of the oil pan 18 can be reduced, and the lubricating oil can be smoothly introduced from the first compartment 21 into the second compartment 22.

Moreover, in the second embodiment, since the lubricating oil crosses over the upper end of the partition wall 24, so that the lubricating oil is introduced from the first compartment 21 into the second compartment 22, the fully deaerated lubricating oil can be introduced into the second compartment 22, certainly preventing the decrease in discharge capacity of the oil pump 36.

(Third Embodiment)

Next, a diluting fuel-in-oil separating apparatus 40 according to the third embodiment will be described. With respect to the a diluting fuel-in-oil separating apparatus 40 according to the third embodiment, the configuration elements that are the same as those of the diluting fuel-in-oil separating apparatus 20 of the first and second embodiments are given the same numerical references, and their descriptions are therefore omitted.

(1) Configuration of Diluting Fuel-In-Oil Separating Apparatus

As shown in FIG. 5, the diluting fuel-in-oil separating apparatus 40 according to the third embodiment is provided with an oil pan 42 having a catch-pan shaped oil vessel 41 at an upper central region. An inner region of the oil vessel 41 is a first compartment 43, and an inner region of a lower portion of the oil container 18 is a second compartment 44, so that the first and second compartments 43 and 44 are vertically disposed. The first compartment 43 is disposed right below the piston 3, which is the lubricated part.

A bubble generator 46 generating bubbles in the lubricating oil in the first compartment 43 is connected to the first compartment 43. The bubble generator 46 includes a plurality of bubble pores 47 formed through a bottom wall 41 a of the oil vessel 41. The plurality of bubble pores 47 have a diameter of approximately 1 mm, and are formed at an equal pitch over an entire surface area of the bottom wall 41 a. A lower wall 49 forming an air space 48 is provided below the bottom wall 41 a of the oil vessel 41, the air space 48 continuing into each of the bubble pores 47. One end of the air piping 31 is connected to the compressor 30 while the other end thereof is connected to the air space 48.

(2) Function of Diluting Fuel-In-Oil Separating Apparatus

Next, the function of the diluting fuel-in-oil separating apparatus 40 having the above-described configuration is described. During engine operation, the lubricating oil circulating in the area around the piston 3 flows through the gap between the piston 3 and cylinder 2, and falls into the first compartment 43 of the oil vessel 41. The area around the piston 3 includes the crankshaft 4, connecting rod 5, piston 3, and the like, which are the lubricated parts of the engine 1. Meanwhile, the lubricating oil circulating in the area around the head returns to the second compartment 44 of the oil pan 42 via the connecting path 37 formed in the cylinder block 1 a and cylinder head 1 b of the engine 1 and connecting the crankchamber 14 to the space 13 inside the cylinder head cover 1 d, or via the chain case or belt case of the engine 1 (not shown). The area around the head includes the camshafts 10 a and 10 b, the driving mechanism, and the like, which are the lubricated parts of the engine 1.

During engine operation, the compressor 30 sends compressed air to the air piping 31 in an open state and then to the bubble pores 47 via the air space 48 so as to generate a large number of bubbles in the lubricating oil in the first compartment 43. The fuel in the lubricating oil in the first compartment 43 is enveloped or lifted by the generated bubbles, so that vaporization of the fuel is accelerated against viscosity resistance of the lubricating oil.

Meanwhile, after the fuel separation by vaporization in the first compartment 43, the lubricating oil crosses over an upper end of the oil vessel 41, and falls and introduced into the second compartment 44. The lubricating oil in the second compartment 44 is forcibly pressure-fed by the oil pump 36 into the lubricated parts of the engine 1 through the oil passage 19 via the oil strainer 35.

(3) Effect of The Embodiment

As described above, the function and effects demonstrated in the third embodiment are substantially similar to those demonstrated in the second embodiment. In addition, the oil pan 42 is provided with the oil vessel 41 in the upper portion. The inner region of the oil vessel 41 is the first compartment 43, and the inner region of the lower portion of the oil pan 42 is the second compartment 44, so that the first and second compartments 43 and 44 are vertically disposed. Thereby, the width of the oil pan 42 can be reduced, and the fully deaerated lubricating oil can be dropped and introduced into the second compartment 44, certainly preventing the decrease in discharge capacity of the oil pump 36.

In addition, in the third embodiment, since the first compartment 43 is disposed right below the piston 3, which is the lubricated part, the lubricating oil having a relatively large amount of the mixed-in fuel directly falls into the first compartment 43. Thereby, the fuel can be more efficiently separated from the lubricating oil in the first compartment 43.

The present invention is not limited to the second and third embodiments, and various modifications may be made depending on a purpose and use without departing from the scope of the invention. Specifically, although the first compartments 21 and 43 are provided with the plurality of bubble pores 27 and 47 through the bottom walls 23 a and 41 a, and one end of the air piping 31 is connected to the compressor 30 while the other end thereof is connected to the bubble generators 26 and 46, in the second and third embodiments, the present invention is not limited to the same. For example, as shown in FIG. 6, the first compartment 21 (or the first compartment 43) may be provided with a bubble generator 52 having a bubble tube 51, to which the one end of the air piping 31 is connected while the other end thereof is connected to the compressor 30, the bubble tube 51 being provided with a plurality of bubble nozzles 50. In this case, it is preferable that the plurality of the bubble nozzles 50 be provided in a downward direction. The reason for this is to prevent the lubricating oil from entering into the bubble tube 51. Exemplary configurations of an bubble tube 51 include a configuration in which a plurality of the liner bubble tubes 51 are provided in a parallel manner, a configuration in which the spiral or bellows bubble tube 51 is provided, and the like.

Although the second compartments 22 and 44 are disposed right below the connecting path 37 in the second and third embodiments, the present invention is not limited to the same. For example, as shown in FIG. 7, in addition to or instead of disposing the second compartments 22 and 44 below the connecting path 37, the second compartments 22 and 44 may be disposed right below a chain case 54 or the belt case of the engine 1.

Although the plurality of bubble pores 27 are formed at an equal pitch over the entire surface area of the bottom wall 23 a of the first compartment 21 of the oil pan 18 in the second embodiment, the present invention is not limited to the same. For example, as shown in FIG. 7, the number of the plurality of bubble pores 27 provided through the bottom wall 23 a of the first compartment 21 may be reduced toward the second compartment 22 in the oil pan 18. Thereby, the more fully deaerated lubricating oil can be introduced into the second compartment 22.

In addition, although the bubbles generators 26 and 46 constantly generate bubbles during engine operation, in the second and third embodiments, the present invention is not limited to the same. For example, the solenoid valve 33 may be controlled to open and close by the controller 32 based on engine speed, oil pressure, oil temperature, and the like of the engine 1. As a result, the fuel can be more efficiently separated when the degree of fuel dilution in the lubricating oil of the engine 1 is relatively high.

Although the lubricating oil circulating in the area around the piston among the lubricated parts of the engine 1 returns to the first compartments 21 and 43 while the lubricating oil circulating in the area around the head returns to the second compartments 22 and 44, in the second and third embodiments, the present invention is not limited to the same. For example, substantially all the lubricating oil circulating through the lubricated parts of the engine 1 may return to the first compartments 21 and 43.

Further, in the second and third embodiments, the first compartments 21 and 43 may be provided with the heater heating the lubricating oil therein to separate the fuel from the lubricating oil by vaporization, in addition to the bubble generators 26 and 46 generating bubbles for the fuel separation by vaporization.

Furthermore, although the bubble generator 26 and 46 are provided in the oil pans 18 and 42 of the wet sump engine in the second and third embodiments, the present invention is not limited to the same. For example, the bubble generator may be provided in an oil tank of a dry sump engine.

The present invention may widely be utilized as a technology for separating the diluting fuel in the lubricating oil of an internal combustion engine. Particularly, the present invention may be suitably used as a diluting fuel-in-oil separating apparatus of a cylinder injection internal combustion engine that performs a secondary fuel injection before and after a primary fuel injection.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular structures, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

The present invention is not limited to the above described embodiments, and various variations and modifications may be possible without departing from the scope of the present invention. 

1. A diluting fuel-in-oil separating apparatus of an internal combustion engine comprising: an oil container configured to contain lubricating oil of the internal combustion engine and have a first compartment and a second compartment divided from the first compartment, such that the lubricating oil is introduced from the first compartment into the second compartment; and a fuel eliminator configured to eliminate fuel from the lubricating oil in the first compartment, wherein, the second compartment is provided with an oil passage having an oil pump configured to supply the lubricating oil from the second compartment to lubricated parts of the internal combustion engine.
 2. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 1, wherein the fuel eliminator comprises a heater configured to heat the lubricating oil of the internal combustion engine; the first compartment is configured to contain the lubricating oil heated by the heater; and the second compartment is divided from the first compartment, such that the lubricating oil heated by the heater is introduced from the first compartment into the second compartment, the diluting fuel-in-oil separating apparatus of the internal combustion further comprising: an oil guide provided in a main body of the internal combustion engine and configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston among the lubricated parts of the internal combustion engine.
 3. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 2, wherein a volume of the oil contained in the first compartment is smaller than that contained in the second compartment.
 4. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 2, wherein the heater heats the lubricating oil flowing from the first compartment into the second compartment.
 5. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 3, wherein the heater heats the lubricating oil flowing from the first compartment into the second compartment.
 6. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 2, wherein a heat source for the heater is exhaust of the internal combustion engine.
 7. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 3, wherein a heat source for the heater is exhaust of the internal combustion engine.
 8. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 1, wherein the fuel eliminator comprises a bubble generator configured to generate bubbles in the lubricating oil in the first compartment.
 9. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 8, wherein a volume of the oil contained in the first compartment is smaller than that contained in the second compartment.
 10. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 8, wherein a main body of the internal combustion engine is provided with an oil guide configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston, which is the lubricated part.
 11. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 9, wherein a main body of the internal combustion engine is provided with an oil guide configured to guide the lubricating oil into the first compartment after the lubricating oil lubricates a piston, which is the lubricated part.
 12. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 8, wherein the first compartment is disposed right below a piston, which is the lubricated part.
 13. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 9, wherein the first compartment is disposed right below a piston, which is the lubricated part.
 14. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 8, wherein the second compartment is disposed right below a passage configured to return the lubricating oil into the oil container after the lubricating oil lubricates an area around a head, which is the lubricated part.
 15. The diluting fuel-in-oil separating apparatus of the internal combustion engine according to claim 9, wherein the second compartment is disposed right below a passage configured to return the lubricating oil into the oil container after the lubricating oil lubricates an area around a head, which is the lubricated part. 